Azo dyestuffs and method of preparing same



Patented Aug. 2, 1932 ENITED vP:Afllli.NT OFFICE EAINALD BRIGHTMAN, OFMANCHESTER, ENGLAND, ASSIGNOR IO IMPERIAL CHEMICAL INDUSTRIES LIMITED,OF WESTMINSTER, ENGLAND AZO DYESTUFFS AND METHOD OF PREPARING- SAME NoDrawing. Application filed August 7, 1530, Serial No; 473,763, and inGreat Britain August 21, 1929.

This invention relates to new azo dyestuffs and the method of theirpreparation. More particularly it relates to dyes prepared from certainamines or aminothiazoles coupled with a l-amino--naphthol-7-sulphonicacid compound.

According to this invention new azo dyes which have the valuableproperty of dyeing viscose silk, that is, regenerated cellulose silk, ineven shades are obtained by diazotizing an unsulphonatednon-carboxylated amine of the benzene or naphthalene series or asulphonated aminothiazole derivative and coupling with1-amino-5-naphthol-7 -sulphonic acid or an N-substituted derivativethereof.

Coupling may be effected either in acid or in alkaline solution, andaccording to the amino compound diazotized there may be obtaineddyestuffs giving red to violet dyeings on viscose silk which arecharacterized by their even shades.

The general formula for these dyes may be represented as follows:

in which It represents an unsulphonated, noncarhoxylated aromaticorganic radical of the andwhen combination is complete, it is heated upand the dyestufi salted out with common salt, giving dark powder whichdyes viscose silk a violet shade.

It probably has the following formula:

Example 2.-319 parts of dehydrothio-ptoluidine sulphonic acid arediazotize'd with 69. parts of sodium nitrite and 300 parts of 36%hydrochloric acid and the suspension of diazo compound is stirred into acold solution of 239 parts of l-amino-5-naphthol-7- sulphonic acidcontaining about 400 parts of sodium carbonate. After stirring untilcombination is complete the coupling is heated up and the dyestui'fisolated by the addition of common salt. It dyes viscose silk in veryeven brownish-violet shades.

It probably has the following formula:

ornQs/ Ewwmple 51-143 parts of wnaphthylamine are diazotized in theknown manner with 69 parts of sodium nitrite and 300 parts of 36%hydrochloride acid. The diazo solution is stirred into a well cooledsolution containing 366 parts of the sodium salt ofl-benzoylamino-5-naphthol-T-sulphonic acid and about 500 parts of sodiumacetate. The coupling is maintained neutral to Congo red paper andstirred until combination is complete when it is made alkaline withsodium carbonate and heated up. The dyestufi which is salted out withcommon salt dyes viscose silk a bluish shade.

It probably has the following formula:

1 NELOO CoHl It will be understood that, while the formulas given hereinin all probability correctly represent the dyes of the presentinvention, the invention is wholly independent of the correctness ofsuch formulas.

As many apparently widely different embodiments of this invention may bemade Without departing from the spirit thereof, it is, to be understoodthat we do not limit ourselves to the foregoing examples or descriptionsexcept as indicated inthe following patent claims:

I claim:

1. The process of preparing a monoazo dyestufi which comprises couplinga diazotized aromatic amine of the benzene or naphthalene seriesselected from the group consisting of such unsulphonatednon-carboxylated aryl amines which do not contain a hydroxyl group andsulphonated amino thiazoles with 1-amino-5-naphthol-7-sulphonic acidcompounds.

2. The process of claim 1 wherein the amine diazotized is o-anisidine.

3. The process of claim 1 wherein the amine diazotized isdehydro-thio-p-toluidine V sulphonic acid.

4. The process of claim 1 wherein the amine diazotized isa-naphthylamine.

5. A dyestulf having the general formula in which R represents anunsulphonated, noncarboxylated aromatic radical of the benzene ornaphthalene series not containing a hydroxyl group and R representshydrogen or an organic radical of the benzene series.

In testimony whereof, I affix my signature.

RAIN ALD BRIGHTMAN.

